@jiuwu This model wasn't extracted by myself ,in fact it's from Deviantart. But you can still use a 3dsmax script from RE modding forum to import models into 3dsmax and at last your model will be exported.

@Andrei_BRDNew Hey,bro.I found out that we can change the magazine model into one bullet,which will solve the problem you mentioned,and I got this idea from the M1014 mod,maybe we can convert the SPAS12-LIKE SHOTGUN in gta5,right?😃